Protection Against Actions of X-rays by Glycerol in the Bacterial Spore

SummaryThe effect of glycerol on the three classes of radiation damage previously recognized in the spores of Bacillus megaterium has been examined. Glycerol was found to reduce the amount of damage associated with each of the classes. The ‘direct’ action component (Class I) is almost certainly involved. It is the presence of glycerol rather than the absence of water that is responsible for the effect. The concentration-effect relationship is described well by the Langmuir adsorption equation, consistent with the notion that protective action is the consequence of physical adsorption on important sites as previously described for vegetative bacterial cells. Extrapolation of the Langmuir relationship to infinite glycerol concentration gives a value of 0 for that portion of the damage unaffected by glycerol. The adsorption sites may be the same as those usually occupied by water. The results indicate also that spores and vegetative cells are affected by radiation in similar manners.